This invention relates generally to door control systems and more particularly to door control systems utilized in mass transit vehicles having power operated doors, wherein it is necessary to accurately determine vehicular speed in order to properly open and close doors in order to insure passenger egress and ingress. Present systems in use are somewhat exemplified by the system disclosed in U.S. Pat. No. 2,637,009. The specification of which is hereby incorporated by reference. Wherein, in a multiple car train, operation of each door is controlled via signals from propulsion equipment and individual relays located in each door circuit. This method of door control, while providing somewhat improved performance in that each door must be closed and a propulsion signal available in order to allow the train to move, suffers from certain shortcomings. Additional door control systems involving operative vehicular interlocks are contained in U.S. Pat. Nos. 1,906,694, 2,096,043, and 1,849,516. Typical door control circuitry is also disclosed in U.S. Pat. Nos. 3,537,403, 1,906,699, 1,849,516, 3,537,403, and 3,782,034. Specification of these U.S. patents are hereby incorporated by reference.
A major shortcoming of these approaches is the ambiguity inherent in the propulsion signal and difficulties in relating car motion to the door control signal. Also possible malfunction of the individual door relay sometimes called a door control summary relay can greatly reduce system reliability. In view of the consequences of premature door opening and/or closing during rapid transit vehicle operation, there has been a substantial need for a system wherein additional checks relative to vehicle speed and condition of the propulsion system are utilized in order to more accurately determine the condition of a given vehicle and/or train prior to any door operation. Additionally, in present systems, possible electrical failures indicating incorrect door vehicle operation information have heretofore been essentially undetectable, resulting in a need for close attention by transit vehicl operators. This requirement, as in the past, resulted in reducing overall effectiveness of the door control system and increasing operation times, a highly undesirable occurrence in todays modern rapid transit systems.
Providing accurate determination of vehicular speed has also been a substantial problem with past systems. Due to the design of speed detectors, exact determination of vehicular speed due to wheel rotation has been subject to substantial error, thus substantially reducing the effectiveness of what is perhaps the best means for allowing doors to open, or in the alternative, closing open doors on start-up.
The invention disclosed here provides an improved control system and method for actuating doors which utilizes, on a time based sample basis, a number of vehicular "state" indications in addition to wheel rotation. Sampling is cyclically repeated in periods chosen to increase the reliability of door control operation.
Accordingly, it is an object of this invention to provide an improved door control system having motion and propulsion signals combined with time based checks for vehicular propulsion to enable door operating sequences.
It is a further object of this invention to provide door controller which utilizes various self-checking techniques to minimize incorrect door operation due to equipment failure.
It is a still further object of this invention to provide a door control system for mass transit vehicles wherein utilization of speed signals in combination determine through recycled logic, a most appropriate time to enable door opening and/or closing.